<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #div1 {
            border: 1px red dashed;
            width: 100px;
            height: 200px;
            padding: 50px;
            /*margin: 50px;*/
            /*上下距离30px，居中*/
            margin: 30px  auto;
        }
        #div2, #div3 {
            border: gray 4px dotted;
            width: 100px;
            height: 100px;
        }
        /*#div3 {*/
            /*border: 1px solid green;*/
            /*width: 100px;*/
            /*height: 200px;*/
        /*}*/
    </style>
</head>
<body>
<div id="div1">div1正文段</div>
<div id="div2">div2</div>
<!--<div id="div3">div3</div>-->
</body>
</html>